4,689 research outputs found

    Parasites component community in wild population of Pterophyllum scalare Schultze, 1823 and Mesonauta acora Castelnau, 1855, cichlids from the Brazilian Amazon.

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    The aim of the present study was to compare the component parasite communities of the Pterophyllum scalare and Mesonauta acoracichlids in the Amazon River system in northern Brazil. From September to December 2012, 42 specimens of P. scalareand 38 specimens of M. acorawere captured using hand nets and gillnets in the Igarape Fortaleza basin, a tributary of the Amazon River in the state of Amapa. Of the P. scalarespecimens examined, 97.6% were parasitized by Ichthyophthirius multifiliis, Tripartiellasp., Trichodina nobilis, Gussevia spiralocirra, Posthodiplostomum sp., Capillaria pterophylli, Ichthyouris sp. and Gorytocephalus spectabilis. Similarly, all specimens of M. acorawere parasitized by I. multifiliis, Tripartiellasp,T. nobilis, Sciadicleithrum joanae, Posthodiplostomum sp., Pseudoproleptus sp., Ichthyouris sp. and G. spectabilis. However, for both hosts the dominance was of I. multifiliisand with an overdispersion of parasites. Parasite communities of P. scalare and M. acorawere similar and only Pseudoproleptussp. and Posthodiplostomum sp. were larvae. Brillouin diversity, parasite species richness and evenness were higher forM. acorathan for P. scalare, which presented a negative correlation of parasite abundance with body size. Both cichlid species had parasite communities characterized by low diversity and low species richness, with a predominance of ectoparasite species and greatest richness of helminth species, with a low abundance of endoparasites. This was the first study on the parasite diversity in wild P. scalareandM. acora

    Use of low-cost class a evapotranspiration pan for reference evapotranspiration estimation in protected and field environments.

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    Currently, there are various methods for determining the Class A pan coefficient (Kp) in estimating reference evapotranspiration (ETo), which is of utmost importance for water management in agriculture. This study aimed to estimate ETo inside and outside agricultural greenhouses using a low-cost constructed Class A pan (TCA-c) method. To estimate ETo, it is necessary to establish the Kp, as ETo is the product of ECA multiplied by Kp. This study employed the calibration method, comparing ETo determined by Penman-Monteith (EToPM) with Class A pan evaporation (ECA) to determine Kp. EToPM served as the standard for correlations with reference evapotranspiration using the TCA-c method inside and outside an agricultural greenhouse, avoiding the installation of a "Class A" pan inside the greenhouse. The experiment was conducted at UFF's Gragoatá campus in Niterói - RJ. Four TCA-c pans were installed (three inside and one outside an agricultural greenhouse) and managed for one year. Principal Component Analyses (PCA) revealed significant differences in ETo throughout the seasons. Adjusted Kps were established for all pans. It was observed that ETo inside the greenhouse was lower than that estimated outside. It is recommended to install the TCA-c pan inside the greenhouse for ETo estimation, utilizing different Kps throughout the seasons

    Static quantities of a neutral bilepton in the 331 model with right-handed neutrinos

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    A neutral vector boson can possess static electromagnetic properties provided that the associated field is no self-conjugate. This possibility is explored in the SUC(3)XSUL(3)XUN(1)SU_C(3) X SU_L(3) X U_N(1) model with right-handed neutrinos, which predicts a complex neutral gauge boson Y0Y^0 in a nontrivial representation of the electroweak group. In this model the only nonvanishing form factors are the CP-even ones, which arise from both the quark and gauge sectors, and contribute to the magnetic dipole and the electric quadrupole moments of this neutral particle.Comment: 10 pages, 6 figures, submitted to Phys. Rev.

    Branching points in the low-temperature dipolar hard sphere fluid

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    In this contribution, we investigate the low-temperature, low-density behaviour of dipolar hard-sphere (DHS) particles, i.e., hard spheres with dipoles embedded in their centre. We aim at describing the DHS fluid in terms of a network of chains and rings (the fundamental clusters) held together by branching points (defects) of different nature. We first introduce a systematic way of classifying inter-cluster connections according to their topology, and then employ this classification to analyse the geometric and thermodynamic properties of each class of defects, as extracted from state-of-the-art equilibrium Monte Carlo simulations. By computing the average density and energetic cost of each defect class, we find that the relevant contribution to inter-cluster interactions is indeed provided by (rare) three-way junctions and by four-way junctions arising from parallel or anti-parallel locally linear aggregates. All other (numerous) defects are either intra-cluster or associated to low cluster-cluster interaction energies, suggesting that these defects do not play a significant part in the thermodynamic description of the self-assembly processes of dipolar hard spheres. © 2013 AIP Publishing LLC

    Nonmonotonic magnetic susceptibility of dipolar hard-spheres at low temperature and density

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    We investigate, via numerical simulations, mean field, and density functional theories, the magnetic response of a dipolar hard sphere fluid at low temperatures and densities, in the region of strong association. The proposed parameter-free theory is able to capture both the density and temperature dependence of the ring-chain equilibrium and the contribution to the susceptibility of a chain of generic length. The theory predicts a nonmonotonic temperature dependence of the initial (zero field) magnetic susceptibility, arising from the competition between magnetically inert particle rings and magnetically active chains. Monte Carlo simulation results closely agree with the theoretical findings. © 2013 American Physical Society

    Sex differences in functional connectivity between resting state brain networks in autism spectrum disorder

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    Functional brain connectivity (FBC) has previously been examined in autism spectrum disorder (ASD) between-resting-state networks (RSNs) using a highly sensitive and reproducible hypothesis-free approach. However, results have been inconsistent and sex differences have only recently been taken into consideration using this approach. We estimated main effects of diagnosis and sex and a diagnosis by sex interaction on between-RSNs FBC in 83 ASD (40 females/43 males) and 85 typically developing controls (TC; 43 females/42 males). We found increased connectivity between the default mode (DM) and (a) the executive control networks in ASD (vs. TC); (b) the cerebellum networks in males (vs. females); and (c) female-specific altered connectivity involving visual, language and basal ganglia (BG) networks in ASD—in suggestive compatibility with ASD cognitive and neuroscientific theories.info:eu-repo/semantics/publishedVersio
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